This invention relates to tubular fabric products and, more particularly, to fabric sleeving providing thermal protection for elongated objects such as automotive exhaust gas recirculation devices and wiring harnesses.
The use of braided or woven fabric sleeves for the protection of cables, hoses and other elongated, flexible articles from the effects of abrasion, high temperatures or the like is well known in the art. Examples selected from a broad spectrum of sleeving products are available from manufacturers such as Bentley-Harris Inc. One such fabric sleeve is a product marketed under the trademark EXPANDO. EXPANDO(copyright) sleeving products are lightweight and provide tough physical protection for cable assemblies, wiring harnesses and the like. Many of these products are typically of an open construction, provide abrasion resistance, allow for the circulation of air and prevent the entrapment of moisture. The substrates are neatly maintained in compact form and are protected against abrasion and the possibility of being individually snagged by moving parts of nearby machinery or the like. Other forms of sleeving products are of relatively closed construction and are fabricated of insulating yarns comprised of materials such as glass fiber for the purpose of providing thermal protection.
Some of the products mentioned are longitudinally slit and provided with fastening means so as to allow them to be used in the bundling of elongated objects which previously have been installed and fastened at both ends. One such product is sold under the trademark EXPANDO ZIP. This product is provided with zipper-type fasteners to allow for fastening around the substrate or substrates. Another such product is a braided product having resiliently set filaments extending transversely of the long axis of the product. The resiliently set filaments cause the side edges of a split sleeve to yieldably close, simplifying installation over previously installed elongated devices.
A product of this type is shown and described in U.S. Pat. No. 5,413,149, granted May 9, 1995. Other examples of sleeving products are shown in U.S. Pat. No. 4,870,887, which shows a braided sleeve comprised of materials such as glass fiber and resilient fiber, and U.S. Pat. No. 4,282,284, which discloses the protection of wires or cables by wrapping with a coated and impregnated fabric tape.
Although the above-identified products have proven to be satisfactory for their intended purposes, the need has existed for the use of a thermal wrap product which is easily fabricated, lends itself to the manufacture of products manufactured from closely woven fabrics and is easily installed on products of irregular shape, as well as for installation on elongated parts which have complex curvatures or have been previously installed.
Products of the invention take advantage of the properties of yarns selected from the group of so-called xe2x80x9chybrid yarnsxe2x80x9d; that is, yarns having more than one material component including, without limitation, over extruded yarns, commingled yarns and DREF process yarns. Especially preferred are yarns of glass or other mineral material combined with a thermoplastic (thermally settable) polymeric material or with wire. The yarns referred to combine the properties of thermal resistance with the capability of having imparted thereto a resilient set. In carrying out the invention, these hybrid yarns are woven into a fabric in which they extend in the fill direction. Thereafter, the hybrid yarns are resiliently set by known means, and the ends of the hybrid yarn form individual hoops with the ends being resiliently urged together and, in some cases, into overlapping relationship with one another.
In carrying out the invention, the hybrid yarns may be resiliently set using techniques described in above mentioned U.S. Pat. No. 5,413,149, which patent is incorporated herein by reference. As used herein and in the ""149 patent, the expression xe2x80x9cresilient setxe2x80x9d or xe2x80x9cresiliently setxe2x80x9d refers to the incorporation of a permanent set or bias in a resilient filamentary material. Such a resilient set is typically imparted by wrapping a sleeve having filaments capable of being resiliently set on a mandrel and providing the set as by the application of heat while the material is maintained in the wrapped condition. Once set, resiliently set filamentary materials tend to return to the set position in the absence of a restraining counter force.
Still another technique useful for carrying out the present invention involves the use of a bendable resilient yarn or wire, such as served stainless steel in the fill direction. By the application of high tension to the wire or yarn on the spools used during the weaving process, a sleeve exhibits a tendency to wrap around the product as the sleeve is woven. The use of wire has the advantage of increasing the temperature resistance and durability of the product.
Objects of the invention include the production of sleeve materials having an insulating capacity and which are particularly useful for wrapping around irregularly shaped objects, such as exhaust gas recirculation devices.
A further object of the invention is the preparation of sleeves which are well adapted for wrapping around previously installed elongated parts which are connected to other equipment at both ends.
A still further object of the invention is the provision of novel sleeving materials having a high insulating capacity and a resistance to abrasion.
Yet another object of the invention is the provision of sleeving material having a reduced tendency to fabric end fray.
The foregoing and other objects of the invention are achieved by the use of fabric sleeves comprised of interwoven glass or similar mineral or ceramic fiber yarns extended in the warp direction and hybrid yarns extended in the fill direction. Preferably, the hybrid yarns used consist essentially of glass or ceramic fibers together with materials within the group consisting of resiliently settable polymeric materials and resilient formable wires and combinations thereof. The wires or hybrid yarns are resiliently set to form resilient hoops yieldably imparting to the fabric side edges a tendency to move into adjacent or overlapping relationship. In accordance with a further aspect of the invention, a reflective film may be bonded to the inner or outer surface of the sleeve. The glass fiber yarns may be coated with a moisture impervious or high temperature resistant polymeric material.
Methodwise, the invention involves weaving to produce a woven product having glass fiber warp yarns and hybrid fill yarns. In one embodiment of the method of the invention, the hybrid fill yarns are resiliently set by placing the woven fabric in a heated folder, applying heat to cause the fill yarns to assume a set in the wrap around or folded condition and then cooling so that the product is resiliently maintained in the set condition. In accordance with a second embodiment, the product is woven on a shuttle loom and one or more wires are used as fill yarns. The wire is fed from pretensioned spools. Weaving fill wire with tension on the spools of wire has been found to impart a resilient set which biases the side edges of the fabric into adjacent and overlapping relationship.